There is a lot of overlap between Rails and React, and you probably could use both to make 90% of the apps out there or more, but what really matters is the 5%

There is a lot of overlap between Rails and React, and you probably could use both to make 90% of the apps out there or more, but what really matters is the 5% that you can only make on Rails and the 5% you can only make on React. Plus the different productivity gains you can get on either for different requirements. If you think there's a "better" solution that will supersede the other for every case, then you probably haven't seen or worked on all kinds of app that benefit from both co-existing.